The scientists who sequenced the marijuana plant say they hope the next generation of pot will have stronger therapeutic compounds. JUAN MABROMATA/AFP/Getty Images hide caption

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A new type of sensor uses flat, flexible electronics printed on a thin rubbery sheet, which can stick to human skin for at least 24 hours. John A. Rogers/Science hide caption

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Early morning cigarettes are a proxy for the level of addiction, researchers say. iStockphoto.com hide caption

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Scientists have found evidence that parts of North America and East Antarctica were joined in a supercontinent called Rodinia 1.1 billion years ago. Robin E. Bell/Lamont-Doherty Earth Observatory hide caption

itoggle caption Robin E. Bell/Lamont-Doherty Earth Observatory

Doctors perform a kidney transplant operation in Spain in 2010. One in three people with kidney failure has antibodies that make it hard to receive a transplant, but a new treatment can get rid of them prior to transplant. Xurxo Lobato/Cover/Getty Images hide caption

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Chinese moviegoers wear 3-D glasses as they watch Avatar in January 2010. AFP/Getty Images hide caption

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